Passive infrared detection systems are known in the art to be used for intrusion detection for example in the field of security or lighting control. A passive infrared detection system is designed to detect the movement of an infrared radiation emitting object (e.g. a person) in an area to be monitored. The system has a detector which includes (as is known in the art) a lens to collect infrared rays, as well as a pyroelectric sensor for generating a signal responsive to the radiation collected by the lens. The lens optically divides the area into zones from which rays can be received. The movement of an infrared radiation emitting object across a zone boundary causes a change in the intensity of infrared radiation impinging on the sensor. Thus movement across a zone boundary will cause a signal to be generated which can be used to generate an alarm signal.
When installing a detector, it is important to place the zone boundaries strategically within the area to be monitored. The conventional method of locating boundaries of optically divided detection zones is to move an infrared emitting object (namely a person) within the area to be monitored and to observe an LED indicator located on the detector of a passive infrared detection system. The LED indicator is turned on when an alarm condition is detected. According to the conventional method, one must keep the LED indicator in constant view. The requirement that the LED be in constant view is a serious impediment to the person locating the zones, since the LED indicator is difficult to see and all movement within the area must be made while facing the LED.